[A3] UG-37 ASME VIII DIV.1 OPENING INSIDE PROJ 1

[boisdechene]

Q: Is the inside projection described in opening calcs
for reinforcement based on the centerline of the
opening? or high point where nozzle outside wall and
the inside diameter of the vessel intersect?

 

[prex]

Not sure to understand your question.
As required by ASME you should take any plane containing the nozzle centerline and check the reinforcement in all those planes: so the inner projection to be used will be the projection lying in the plane under examination.
To simplify you may of course take the minimum projection in all planes. prex
motori@xcalcsREMOVE.com

http://www.xcalcs.com

Online tools for structural design

 

[apiguy]

Boisdechene,

If you look at the diagram on page 47 of the 2001 ASME Section VIII Div.1 code, locate "h" on the lower left hand side of the picture. Now flip over to page 46 and read the description of the nomenclature which refers you to UG 40 on page 51 and one should find that the inside projection does indeed imply to the distance from the shell internal surface to the end of the nozzle(but not exceeding the limits in UG-40.

But the problem is where the nozzle located on the side of the vessel. Due to the curvature of the shell, inserting a nozzle with 2" internal projection on the bottom of the nozzle will require a longer portion at the top of the opening.

I am repairing a brand new waste gas burner assembly today due to this very problem. The design specified 6" internal projection, but the manufacturer only inserted the nozzle only 3/4" at the top, then cut the nozzle too short which left approx. 1/2" gap between the nozzle end and the shell which was unsuccessfully bridged with a four pass fillet weld. Richard Schram
Mechanical Integrity Specialist
Pharmacia Global Supply Arecibo-P. Rico
rschram@pharmacia.com

 

[Halket]

The minimum internal projection is taken in the plane being considered. For example, if you were to take a 'cut' of a vertical tower (looking down), the shell would be curved (to the diameter). For this purpose, lets assume your nozzle has a 1/2" (12mm) internal projection on the 'short side' (at the OD of the pipe neck) and, due to the curvature, the nozzle has an internal projection of 3/4" at the 'long side' (at the centerline). You would claim the 1/2" projection for calculation purposes (since it matches the 'curvature plane' - parallel to the vessel shell).

Hope that this helps....

Steve Halket